Natural-Color Pink, Purple, Red, and Brown Diamonds: Band of Many Colors

Among fancy-color diamonds, naturally pink to red stones are among the rarest and most valuable. The color origin for natural pink diamonds is due to either absorption from the as-yet-unidentified "550 nm" defect(s) that are correlated with shear stress and natural plastic deformation or, very rarely, the NV0/- centers (nitrogen combined with a vacancy). In this article we summarize prior research as well as the physical characteristics of more than 90,000 natural pink, orangy pink, red, purple, and brown diamonds from the internal GIA database. (Browns and purples are included here, as they coexist on a color continuum with pink diamonds.) We also present absorption and luminescence spectra on a representative subset of 1,000 diamonds to provide an unparalleled gemological and spectroscopic description of these rare gemstones. For pink diamonds, the gemological observations closely correlate with diamond type and the extent of nitrogen aggregation (i.e., type laAB, and type Ila pinks show distinct characteristics). Since type laA更多